Effect of size distribution of the particulate material on the specific breakage rate of particles in dry ball milling

In the dry ball milling operation, the specific breakage rate of particles has been found to vary significantly with the size distribution of the particulate material. However, due to the lack of suitable experimental data and a clear understanding of the role of inter-particle interactions in determining the specific breakage rate of particles, it has not been possible to develop a general mathematical model that can be used to describe the variation of the specific breakage rate of particles. These limitations were overcome in our investigation by using feed charges for batch grinding experiments that were prepared according to specially designed continuous and discontinuous particle size distributions. A detailed analysis of the experimental results led to several new findings about the nature of the non-linear grinding kinetics. In particular, it was found: (i) for a given size fraction of particles, while the effect of the coarser and immediately finer sizes on its specific breakage rate was negative, the effect of the other finer sizes was positive and it increased as the particle size decreased, (ii) the overall effect varied with the material type and particle size, being more pronounced in the case of the softer material and coarse particles, (iii) the breakage distribution parameters were also significantly affected by the particle size distribution, and (iv) a simple linear relationship in terms of the mass fractions of different sizes described the variation of the specific breakage rate parameters with particle size distribution quite satisfactorily. (C) 2016 Elsevier B.V. All rights reserved.